Theoretical study on the molecular mechanism of the domino cycloadditions between dimethyl acetylenedicarboxylate and naphthaleno- and anthracenofuranophane

AM1, B2LYP/6-31G*//AM1, and B3LYP/6-31G* computational studies were perform ed to select the reaction pathway controlling the reactions between dimethy l acetylenedicarboxylate (DMAD) and two furanophanes, naphthalenofuranophan e and anthracenofuranophane. For these domino reactions, several pathways h ave been characterized on the potential energy surface corresponding to two consecutive cycloadditions. The first step corresponds to a [4 + 2] interm olecular cycloaddition of DMAD with the furan ring or with the naphthalene or anthracene ring of both furanophane systems to yield an oxabicyclo[2.2.1 ]heptadiene or a bicyclo[2.2.2]octadiene intermediate, respectively. The se cond step corresponds to [4 + 2] intramolecular cycloadditions of these int ermediates. For the naphthalenofuranophane, the most favorable reaction pat hway takes place along the initial [4 + 2] intermolecular cycloaddition inv olving the nonsubstituted ring of the naphthalene system to give a benzobic yclo[2.2.2]octadiene intermediate, which by a [4 + 2] intramolecular cycloa ddition between the substituted double bond of this intermediate and the fu ran ring affords the final cycloadduct. For the anthracenofuranophane, the most favorable reaction pathway takes place along the initial [4 + 2] inter molecular cycloaddition involving the furan ring to give an oxabicyclo[2.2. 1]heptadiene intermediate, which by a [4 + 2] intramolecular cycloaddition between the nonsubtituted double bond of the bicyclic system and the naphth alene system affords the final cycloadduct. An analysis of energetic contri butions to the potential energy barriers identifies the different factors c ontrolling the competitive reaction pathways. The present theoretical resul ts are able to explain the available experimental data.